Contrast of a projection image are improved in a projector having a liquid crystal light modulation device equipped with an optical compensation element as referred to in Japanese Patent Publication No. JP-A-2003-131320. According to the projector(s) in the related art, since the optical compensation element is provided, birefringence (an optical phase difference caused by liquid crystal molecules) caused by the pretilt angle of the liquid crystal panel may be compensated, and as a result, the contrast of the projection image may be improved.
As the optical compensation element, there are known inorganic material-based optical compensation elements besides organic material-based optical compensation elements (e.g., a stretched retardation film). The inorganic material-based optical compensation element has an inorganic birefringent optical compensation plate made, for example, of quartz or sapphire. Such an inorganic material-based optical compensation element has advantages of being superior in heat resistance, in heat radiating property, and in light stability, longer operating life, and good in-plane uniformity of refractive index anisotropy.
It should be noted that the inorganic optical compensation plate in the optical compensation element is thinned by grinding and polishing with, for example, a grinding/polishing device to be a thin sheet, and since such a thin inorganic optical compensation plate is difficult to treat by itself, the thin inorganic is used in the condition in which the thin inorganic optical compensation plate is bonded on a surface of a light transmissive support substrate with a predetermined thickness.
Incidentally, in the past, as a method of manufacturing the optical compensation element equipped with the inorganic optical compensation plate and the light transmissive support substrate, there has been a method of grinding and polishing an inorganic substrate made of a birefringent inorganic material temporarily attached to a grinding/polishing plate so as to have a predetermined thickness, then separating the inorganic substrate thus ground and polished from the grinding/polishing plate, and then bonding the inorganic substrate thus separated with the light transmissive support substrate with, for example, an adhesive.
However, in the manufacturing method of the optical compensation element in the related art, since the inorganic substrate thus ground and polished is extremely thin (e.g., no thicker than 10 μm), handling of the inorganic substrate thus ground and polished when separating it from the grinding/polishing plate or when bonding it with the light transmissive support substrate is not easy, and consequently, manufacturing the optical compensation element is not easy.
Further, during handling there is a high risk of damaging the inorganic substrate which is ground and polished according to the existing manufacturing method(s) of the optical compensation element in the related art, making a reduction of manufacturing cost difficult.